From 153bf27f3edbb1af1c6fcc5e2c3a026f6bfd0551 Mon Sep 17 00:00:00 2001
From: Alexander Kireev <ak.chatman.media@gmail.com>
Date: Wed, 1 Jul 2026 04:47:01 +0700
Subject: [PATCH] fix(routing): match ws(s) baseURL rewrite case-insensitively

toWebSocketBaseUrl() only rewrote http(s) to ws(s) when the scheme was
lowercase, so a baseURL like 'HTTP://x.com' was left untouched and
routeWebSocket()/waitForEvent('websocket') would never match. Schemes
are case-insensitive per RFC 3986, and the rest of urlMatch.ts already
treats them that way, so do the same here.
---
 packages/isomorphic/urlMatch.ts        |  7 ++++---
 tests/library/route-web-socket.spec.ts | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/packages/isomorphic/urlMatch.ts b/packages/isomorphic/urlMatch.ts
index 455147898098f..30cd9a95694d0 100644
--- a/packages/isomorphic/urlMatch.ts
+++ b/packages/isomorphic/urlMatch.ts
@@ -202,9 +202,10 @@ export function resolveGlobToRegexPattern(baseURL: string | undefined, glob: str
 }
 
 function toWebSocketBaseUrl(baseURL: string | undefined) {
-  // Allow http(s) baseURL to match ws(s) urls.
-  if (baseURL && /^https?:\/\//.test(baseURL))
-    baseURL = baseURL.replace(/^http/, 'ws');
+  // Allow http(s) baseURL to match ws(s) urls. Schemes are case-insensitive,
+  // same as elsewhere in this file, so 'HTTP://...' should be rewritten too.
+  if (baseURL && /^https?:\/\//i.test(baseURL))
+    baseURL = baseURL.replace(/^https?/i, scheme => scheme.toLowerCase() === 'https' ? 'wss' : 'ws');
   return baseURL;
 }
 
diff --git a/tests/library/route-web-socket.spec.ts b/tests/library/route-web-socket.spec.ts
index d968889490b4a..21b1b7efc1c45 100644
--- a/tests/library/route-web-socket.spec.ts
+++ b/tests/library/route-web-socket.spec.ts
@@ -646,6 +646,30 @@ test('should work with baseURL', async ({ contextFactory, server }) => {
   ]);
 });
 
+test('should work with baseURL regardless of scheme casing', async ({ contextFactory, server }) => {
+  // baseURL schemes are case-insensitive, same as everywhere else in URL matching.
+  const context = await contextFactory({ baseURL: 'HTTP://' + server.HOST });
+  const page = await context.newPage();
+
+  await page.routeWebSocket('/ws', ws => {
+    ws.onMessage(message => {
+      ws.send(message);
+    });
+  });
+
+  await setupWS(page, server, 'blob');
+
+  await page.evaluate(async () => {
+    await window.wsOpened;
+    window.ws.send('echo');
+  });
+
+  await expect.poll(() => page.evaluate(() => window.log)).toEqual([
+    'open',
+    `message: data=echo origin=ws://${server.HOST} lastEventId=`,
+  ]);
+});
+
 test('should expose protocols to the route handler', async ({ page, server }) => {
   const routes: WebSocketRoute[] = [];
   await page.routeWebSocket(/.*/, ws => {